Yonsei Med J.  2010 Mar;51(2):212-218. 10.3349/ymj.2010.51.2.212.

Day-to-Day Differences in Cortisol Levels and Molar Cortisol-to-DHEA Ratios among Working Individuals

• Kim MS
• Lee YJ
• Ahn RS

• KMID: 1126020
• DOI: http://doi.org/10.3349/ymj.2010.51.2.212

Abstract

PURPOSE
The present study was carried out to determine day-to-day differences in cortisol levels and the molar cortisol-to-dehydroepiandrosterone (DHEA) ratio (molar C/D ratio) in working subjects. MATERIALS AND METHODS: The cortisol and DHEA levels were measured from saliva samples collected 30 minutes after awakening for 7 consecutive days in full-time working subjects that worked Monday through Saturday. To determine the day-to-day differences within subjects, the collected data was analyzed using variance (ANOVA) for a randomized complete block design (RCBD). RESULTS: The cortisol levels from samples collected 30 minutes after awakening on workdays were similar to each other, but were significantly different from the cortisol levels on Sunday. The DHEA levels were not significantly different between the days of week. The DHEA levels on Monday and Tuesday were relatively lower than the levels on the other weekdays. The DHEA levels on Thursday and Friday were relatively higher than the other days. The molar C/D ratios on Sunday were significantly lower than those on workdays. The molar C/D ratios on Monday and Tuesday were significantly higher than those on Wednesday or other workdays. CONCLUSION: The cortisol levels and the molar C/D ratios demonstrate differences in adrenocortical activities between workdays and non-workdays, but the molar C/D ratio additionally represents differences in adrenocortical status between the first two workdays and other workdays. Thus, it is possible that the day-to-day differences in the cortisol levels and the molar C/D ratio represent the adrenal response to upcoming work-related stress.

Keyword

Salivary cortisol; salivary DHEA; weekly cortisol rhythm; weekly molar cortisol-to-DHEA ratio rhythm; working individuals

MeSH Terms

Adult
Analysis of Variance
Dehydroepiandrosterone/*metabolism
Female
Humans
Hydrocortisone/*metabolism
Male
Middle Aged
Saliva/chemistry
Work/*physiology

Figure

• 

  Fig. 1 Changes in the cortisol levels at different periods after awakening. The cortisol levels were determined from salivary samples collected immediately upon awakening and 15, 30 and 45 minutes after awakening on workdays from 26 full-time working subjects. Each box in panel represents the interquartile range, whiskers represent range, and the horizontal line and the cross symbol within the box represent the median and mean values of cortisol, respectively. The mean cortisol levels were analyzed by one-way analysis of variance (ANOVA) and Tukey's multiple range test. Boxes with different letters are significantly different from each other (p < 0.05).

• 

  Fig. 2 Changes in the cortisol levels from Monday through Sunday. The cortisol levels were determined from the saliva samples collected 30 minutes after awakening from 28 full-time working subjects for 7 consecutive days. Each bar in the panel represents the mean and standard deviation. The day-to-day differences in the cortisol levels were analyzed by using analysis of variance (ANOVA) for a randomized complete block design (RCBD) and post-hoc test (Duncan's multiple-range test). Bars with different letters are significantly different from each other (p < 0.05).

• 

  Fig. 3 Changes in the DHEA levels from Monday through Sunday. The DHEA levels were determined from the saliva samples collected 30 minutes after awakening from 28 full-time working subjects for 7 consecutive days. Each bar in the panel represents the mean and standard deviation. The day-to-day differences in the DHEA levels were analyzed by using analysis of variance (ANOVA) for a randomized complete block design (RCBD) and post-hoc test (Duncan's multiple-range test). Bars with different letters are significantly different from each other (p < 0.05). DHEA, dehydroepiandrosterone.

• 

  Fig. 4 Changes in the molar cortisol to DHEA (C/D) ratios from Monday through Sunday. The molar C/D ratios were calculated from the simultaneously determined cortisol and DHEA levels from a sample collected 30 minutes after awakening from 28 full-time working subjects for 7 consecutive days. Each bar in the panel represents the mean and standard deviation. The day-to-day differences in the molar C/D ratios were analyzed by using analysis of variance (ANOVA) for a randomized complete block design (RCBD) and post-hoc test (Duncan's multiple-range test). Bars with different letters are significantly different from each other (p < 0.05). DHEA, dehydroepiandrosterone; C/D ratio, cortisol-to-DHEA ratio

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